Em Fri, Jun 23, 2017 at 02:48:24PM +0900, Namhyung Kim escreveu: > Even every module has loaded onto same addresses, some modules can be > changed and reloaded.
Can you rephrase the above statement? You mean even if a module is reloaded at the same address it can have a different symtab and thus misresolve symbols if we get a sample for one module version and try to resolve symbols using a symtab for another module version? > In that case it needs to access to the old module > in the build-id cache. Right, we need to make sure that during a 'perf record' session a módule isn't reloaded, because at 'perf record' exit we will record that module build-id in a perf.data header and grab a copy (or a hardlink, if possible) into the ~/.debug build-id cache, then, at 'perf report' time we will read that build-id perf.data table and lookup in the build-id cache to get the matching symtab (and full elf .ko file to do things like annotation). - Arnaldo > Cc: Adrian Hunter <[email protected]> > Cc: Wang Nan <[email protected]> > Signed-off-by: Namhyung Kim <[email protected]> > --- > tools/perf/util/symbol.c | 45 +++++++++++++++++++++++---------------------- > 1 file changed, 23 insertions(+), 22 deletions(-) > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > index ce79a51f25bf..fe46eb782297 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -1155,6 +1155,7 @@ static int dso__load_kcore(struct dso *dso, struct map > *map, > int err, fd; > char kcore_filename[PATH_MAX]; > struct symbol *sym; > + struct map_groups old_mg; > > if (!kmaps) > return -EINVAL; > @@ -1196,15 +1197,8 @@ static int dso__load_kcore(struct dso *dso, struct map > *map, > goto out_err; > } > > - /* Remove old maps */ > - old_map = map_groups__first(kmaps, map->type); > - while (old_map) { > - struct map *next = map_groups__next(old_map); > - > - if (old_map != map) > - map_groups__remove(kmaps, old_map); > - old_map = next; > - } > + old_mg = *kmaps; > + kmaps->maps[map->type].entries = RB_ROOT; > > /* Find the kernel map using the first symbol */ > sym = dso__first_symbol(dso, map->type); > @@ -1223,24 +1217,31 @@ static int dso__load_kcore(struct dso *dso, struct > map *map, > while (!list_empty(&md.maps)) { > new_map = list_entry(md.maps.next, struct map, node); > list_del_init(&new_map->node); > - if (new_map == replacement_map) { > - map->start = new_map->start; > - map->end = new_map->end; > - map->pgoff = new_map->pgoff; > - map->map_ip = new_map->map_ip; > - map->unmap_ip = new_map->unmap_ip; > - /* Ensure maps are correctly ordered */ > - map__get(map); > - map_groups__remove(kmaps, map); > - map_groups__insert(kmaps, map); > - map__put(map); > - } else { > - map_groups__insert(kmaps, new_map); > + > + map_groups__insert(kmaps, new_map); > + > + if (new_map != replacement_map) { > + old_map = map_groups__find(&old_mg, new_map->type, > new_map->start); > + if (old_map && dso__loaded(old_map->dso, > old_map->type)) { > + new_map->pgoff = old_map->pgoff; > + > + dso__put(new_map->dso); > + new_map->dso = dso__get(old_map->dso); > + } > } > > map__put(new_map); > } > > + /* Remove old maps */ > + old_map = map_groups__first(&old_mg, map->type); > + while (old_map) { > + struct map *next = map_groups__next(old_map); > + > + map_groups__remove(&old_mg, old_map); > + old_map = next; > + } > + > /* > * Set the data type and long name so that kcore can be read via > * dso__data_read_addr(). > -- > 2.13.1
